Recently, the treatment in which a stent is placed in a stenosis portion to expand the stenosis portion has been performed in stenotic diseases (tumors, inflammation, and the like) of vessels of living organisms such as blood vessels and alimentary canals. As examples of the stent, metallic and synthetic resin stents are known. Among these, metallic stents require a surgical procedure when being removed from the body, and thus, impose a heavy burden on a patient. Therefore, metallic stents are limited to uses in cases when placement is semi-permanent and cases such as malignant tumors in which a surgical procedure has been planned. Due to these circumstances, a biodegradable stent as a synthetic resin stent has been proposed as the stent which is used in cases in which a metallic stent cannot be used.
The biodegradable stent is formed in a cylindrical shape by knitting biodegradable fibers made of synthetic resin, and decomposes in the blood vessels and the alimentary canals over time, and thus, removal of the stent from the body is not necessary. It is expected that the biodegradable stent will alleviate the burden on the patient by being used for, especially, benign stenotic diseases.
A stent, generally, expands the stenosis portion by being brought close to the stenosis portion in a state of contracted diameter and expanding the diameter of the stent. For example, as a method for bringing the biodegradable stent close to the stenosis portion, a method using an endoscope is known. In this method, the stent in a state of contracted diameter is stored in a thin tubular member referred to as a delivery system, and this delivery system is inserted from a forceps port to the inside of the endoscope to bring the stent close to the stenosis portion.
As described above, the stent is brought close to the stenosis portion in a state of contracted diameter and then the stent is expanded in diameter. Meanwhile, when a stent is placed in a stenosis portion and restenosis is caused in the intestinal tract and the like, the stent sometimes reduces its diameter due to the pressure applied radially from the outside. In particular, a biodegradable stent made of synthetic resin fibers has a lower strength compared to a metallic stent, and it is difficult to obtain resistance sufficient to withstand clinical use, against the pressure applied radially from the outside in a state of expanded diameter.
With regard to this type of problem, a technology for providing a biodegradable stent with resistance to the pressure applied radially from the outside by arranging reinforcing beams extending along the axial direction of a cylindrical portion of the biodegradable stent has been disclosed (for example, refer to Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2009-160079